A new state law requires all secondary students to provide proof of vaccination. The first day at L.A. Unified year-round schools bodes ill for the fall.

Thousands of Los Angeles area students, who began school Tuesday at campuses on a year-round schedule, had not met the deadline for getting the mandatory whooping cough vaccine, providing officials with a glimpse into what could confront them in the fall.

The 8,700 Los Angeles Unified School District students who faced Tuesday's deadline were those attending Bell, Fremont and Huntington Park high schools as well as Gage Middle School in Huntington Park and Ochoa Learning Center in Cudahy. The district dispatched 23 extra nurses to those schools to review vaccination records.

The situation at Huntington Park High was the worst. Of 2,420 students due in class, 1,840 — or 76% — had no proof that they had been vaccinated. Students were given temporary passes to stay in school.

Officials in the state's largest district said that Tuesday's difficulties do not bode well for the fall, when more than 250,000 students in grades seven through 12 are required under state law to have received the vaccine.

"I'm very worried," said Kimberly Uyeda, the district's director of student medical services. "Everyone who's seen what's going on in the last few days would be worried."

The problem is exacerbated because parents are not used to getting older children vaccinated as a requirement for school, Uyeda said. Nor are healthcare providers in as frequent contact with older students, and secondary schools don't typically enforce vaccination regulations. Elementary schools confirm vaccine records for about 50,000 students per year.

The state law took effect Friday. It requires all secondary students to show proof that they have had the booster shot.

State officials insist they've done their part to get the word out, starting with notifying school districts in October, after the measure was signed into law Sept. 29.

The 2010 epidemic of whooping cough, or pertussis, was the largest to hit the state in decades, and health officials said unimmunized teenagers were a factor in the disease's spread.

Some elements of the outreach campaign are recent, including a radio campaign that began last week.

State public health officials were aware that year-round schools started this month, said Ken August, a California Department of Public Health spokesman, and attempted to target them.

"Our efforts were directed at all schools," he said, adding that "different schools and school districts have approached this mandate in different ways."

L.A. Unified sent parents a letter in recent weeks and began a Web page; schools have posted fliers and used automated calling systems and outdoor message boards. Some 7,000 students, most of them uninsured, recently received the Tdap booster — for tetanus, diphtheria and pertussis — through a school-based vaccination campaign.

The staff at Bell High worked through the weekend to contact more than 1,000 students: 500 brought proof that they had the vaccine; 800 others were given a consent form, said Principal Frank Vasquez. At Gage, 600 students reported to school without a record of the vaccine. At Fremont, 150 students received the vaccine Tuesday in a collaboration with the county health department. An additional 350 doses are available there.

Huntington Park High faced an additional hurdle: It's one of seven persistently low-performing schools, where teachers had to reapply for their jobs: 70% of the faculty is new as well as nearly the entire administrative team.

Just before the start of the school day, the situation briefly became chaotic as more students were streaming off campus and onto the streets than were going inside. They'd been told, mistakenly, that without proof of vaccination they had to leave.

Principal Lupe Hernandez's instructions to her staff had been that students be released only to parents. Most students without proof of vaccination were sent to the cafeteria, the gym or the auditorium, where records were checked and forms distributed, including a blue sheet that became a one-day pass, allowing students to remain in school the first day.

"I wasn't aware we needed the immunization," said junior Eric Morales, who stood in line in the boys gym to get his class schedule. "I'm going to have to make an appointment at the clinic to get the shot, hopefully after school."

Also in line was senior Ramon Gonzalez, who got the shot in 2008 but didn't have proof. He also didn't have his blue sheet. So he had to leave for another line in the cafeteria.

There, Barbara Woodard-Cox, the district's head nurse for communicable diseases, was getting the message out. "If you don't bring this back, you can't come to school tomorrow," she said, handing out forms.

At 11:15 a.m., instructor Mercedes Felix had only 12 of 24 students in her algebra class. One was ninth-grader Martha Jasso, who had turned in her vaccination form days ago.

By day's end, more than 300 Huntington Park students were cleared after providing proof of receiving the shot. And by noon, the longer line, stretching the length of the main hall, was to fix course schedules.